The present invention is in the field of processes for making alkylbenzenesulfonate surfactants. The processes herein include a combination of two essential steps, delinearization and alkylation. The delinearization step selected herein introduces particular types of limited branching into an aliphatic hydrocarbon having ten or more, but no more than about 16, carbon atoms. The hydrocarbon includes olefin having a hydrocarbon chain length suitable for detergent manufacture, e.g., C10-C14, or a corresponding paraffin. The second essential step is an alkylation step having an internal isomer selectivity of from 0 to no more than about 40 in which the hydrocarbon is used to monoalkylate benzene catalytically with an alkylation catalyst. Such alkylation catalysts preferably comprise an at least partially crystalline porous zeolite-containing solid, the zeolite having moderate acidity and intermediate pore size. Preferred alkylation catalysts include certain at least partially dealuminized acidic nonfluoridated mordenites. The processes herein further comprise sulfonating, neutralizing and incorporating the resulting modified alkylbenzenesulfonate surfactants into consumer products. The invention relates also to the products of the processes, including modified surfactants and consumer cleaning products containing them.
Historically, highly branched alkylbenzenesulfonate surfactants, such as those based on tetrapropylene (known as xe2x80x9cABSxe2x80x9d or xe2x80x9cTPBSxe2x80x9d) were used in detergents. However, these were found to be very poorly biodegradable. A long period followed of improving manufacturing processes for alkylbenzenesulfonates, making them as linear as practically possible (xe2x80x9cLASxe2x80x9d). The overwhelming part of a large art of linear alkylbenzenesulfonate surfactant manufacture is directed to this objective. Large-scale commercial alkylbenzenesulfonate processes in use in the U.S. today are directed to linear alkylbenzenesulfonates. However, linear alkylbenzenesulfonates are not without limitations; for example, they would be more desirable if improved for hard water and/or cold water cleaning properties.
In the petroleum industry, various processes have more recently been developed, for example for producing low viscosity lube oil, which the inventors have now discovered provide new insight on how to delinearize hydrocarbons to a limited and controlled extent. Such deliberate delinearization, however, is not a feature of any current commercial processes in the different field of alkylbenzenesulfonate surfactant manufacture for consumer products. This is not surprising, in view of the overwhelming volume of LAS surfactant art teaching toward linear compounds and away from delinearization.
The majority of commercial processes for making alkylbenzenes rely on HF or aluminum chloride catalyzed alkylation of benzene. Quite recently, it has been discovered that certain zeolite catalysts can be used for alkylation of benzene with olefins. Such a process step has been described in the context of otherwise conventional processes for manufacture of linear alkylbenzenesulfonates. For example, the DETAL(copyright) process of UOP uses a zeolite alkylation catalyst. The DETAL(copyright) process and all other current commercial processes for alkylbenzenesulfonate manufacture are believed to fail to meet the internal isomer selectivity requirements of the inventive process and alkylation catalyst defined hereinafter. Moreover, the DETAL(copyright) process catalyst or catalysts are believed to lack the moderate acidity and intermediate pore size of alkylation catalysts used in the processes of the present invention. Other recent literature describes the use of mordenite as an alkylation catalyst, but no such disclosure makes the combination of specific process steps required by the instant invention. Moreover, in view of the linearity desired in alkylbenzenesulfonate products of conventionally known processes, they also generally include steps directed to the provision or making of a substantially linear hydrocarbon, not a delinearized one, prior to the alkylation. A possible exception is in U.S. Pat. No. 5,026,933 which includes, for example, oligomerization of lower olefin such as propylene under narrowly defined conditions using collidine-deactivated ZSM-23 to form a composition comprising a tetramer assertedly having 1.3 methyl branches per chain, followed by fractionation and an alkylation using mordenite catalyst. See Example XVII. See also U.S. Pat. No. 4,990,718 in which an alkylbenzene is made via a process that produces a vinylidene olefin by dimerization in presence of chromium catalyst but in which the vinylidene yield is adversely affected by oligomerization and in which distillation is required prior to alkylation. However, the processes of ""933 and ""718 have numerous shortcomings from the standpoint of the detergent industry in terms of cost, catalyst limitations in the propylene oligomerization or olefin dimerization stage, presence of large volumes of distillation fractions that would need to be discarded or find nondetergent customers, and limited range of product compositions, including mixtures of chainlengths attainable. Such developments by the petroleum industry are, in short, not optimal from the standpoint of the expert formnulator of detergent products.
U.S. Pat. No. 5,026,933; U.S. Pat. No. 4,990,718; U.S. Pat. No. 4,301,316; U.S. Pat. No. 4,301,317; U.S. Pat. No. 4,855,527; U.S. Pat. No. 4,870,038; U.S. Pat. No. 2,477,382; EP 466,558, Jan. 15, 1992; EP 469,940, Feb. 5, 1992; FR 2,697,246, Apr. 29, 1994; SU 793,972, Jan. 7, 1981; U.S. Pat. No. 2,564,072; U.S. Pat. No. 3,196,174; U.S. Pat. No. 3,238,249; U.S. Pat. No. 3,355,484; U.S. Pat. No. 3,442,964; U.S. Pat. No. 3,492,364; U.S. Pat. No. 4,959,491; WO 88/07030, Sep. 25, 1990; U.S. Pat. No. 4,962,256, U.S. Pat. No. 5,196,624; U.S. Pat. No. 5,196,625; EP 364,012 B, Feb. 15, 1990; U.S. Pat. No. 3,312,745; U.S. Pat. No. 3,341,614; U.S. Pat. No. 3,442,965; U.S. Pat. No. 3,674,885; U.S. Pat. No. 4,447,664; U.S. Pat. No. 4,533,651; U.S. Pat. No. 4,587,374; U.S. Pat. No. 4,996,386; U.S. Pat. No. 5,210,060; WO 95/17961, Jul. 6, 1995; WO 95/18084; U.S. Pat. No. 5,510,306; U.S. Pat. No. 5,087,788; U.S. Pat. No. 5,625,105 and U.S. Pat. No. 4,973,788 are useful by way of background to the invention. The manufacture of alkylbenzenesulfonate surfactants has recently been reviewed. See Vol. 56 in xe2x80x9cSurfactant Sciencexe2x80x9d series, Marcel Dekker, New York, 1996, including in particular Chapter 2 entitled xe2x80x9cAlkylarylsulfonates: History, Manufacture, Analysis and Environmental Propertiesxe2x80x9d, pages 39-108 which includes 297 literature references. Documents referenced herein are incorporated in their entirety.
The present invention is predicated on an unexpected discovery that combining a specifically defined delinearization step or steps of a non-lower olefin or paraffin (xe2x80x9cnon-lowerxe2x80x9d meaning having 10 or more carbon atoms) with a particularly defined selective alkylation step results in an unexpectedly superior alkylbenzenesulfonate surfactant product.
Accordingly, in one aspect, the present invention relates to a process for preparing modified alkylbenzenesulfonate surfactant suitable for use in cleaning products such as laundry detergents, hard surface cleaners, dishwashing detergents and the like, said process comprising (a) reducing the linearity of an olefin, preferably one having molecular weight of at least about 126 and no more than about 280, preferably no more than about 224, by a step of skeletally isomerizing, in the presence of a constrained skeletal isomerization catalyst, a substantially linear olefin preformed to have at least said molecular weight; and (b) a monoalkylation step having low internal isomer selectivity (from 0 to no more than 40 preferably from 0 to no more than 20, more preferably from 0 to no more than 10 using measures further defined hereinafter), of reacting the product of step (a) with an aromatic hydrocarbon selected from benzene, toluene and mixtures thereof in the presence of a particularly defined alkylation catalyst. Such catalyst comprises a moderate acidity, medium-pore zeolite defined in detail hereinafter. A particularly preferred alkylation catalyst comprises at least partially dealuminized acidic nonfluoridated mordenites.
In another aspect, the invention relates to a process for preparing modified alkylbenzenesulfonate surfactant suitable for use in cleaning products, said process comprising (a) a step of arriving at (making or providing) a reduced-linearity alkylating agent selected from an olefin having molecular weight, n, of at least about 126 and no more than about 280 and produced by a sequence of steps comprising: (i) skeletally isomerizing a linear paraffin having molecular weight of n+2 where n is said molecular weight of said olefin; and (ii) dehydrogenating the isomerized paraffin; and (b) a monoalkylation step of reacting the reduced-linearity alkylation agent of stage (a) (that is, the hydrocarbon produced in that stage) with an aromatic hydrocarbon selected from benzene, toluene and mixtures thereof in the presence of an alkylation catalyst identical with that which is used in the embodiment described in the preceding paragraph.
The invention also encompasses a process according to either of the foregoing aspects or embodiments of the invention having the additional steps, of (c) sulfonating the product of step (b); and one or more steps selected from (d) neutralizing the product of step (c); and (e) mixing the product of step (c) or (d) with one or more cleaning product adjunct materials; thereby forming a cleaning product.
Moreover the invention also encompasses cleaning products including heavy-duty and light-duty laundry detergents, hard surface cleaners, dishwashing detergents, laundry bars, detergent tablets or detergent gels, shampoos and the like formed by any of the processes described.
All percentages, ratios and proportions herein are by weight, unless otherwise specified. All temperatures are in degrees Celsius (xc2x0 C.) unless otherwise specified. All documents cited are in relevant part, incorporated herein by reference.